Filter assembly with modular relief valve interface

ABSTRACT

A fluid filter assembly for filtering a fluid includes a housing base portion having an axially extending tube, a housing cover that is connected to the housing base portion to define an interior space, a filter element, and an interface structure. The filter element is disposed within the interior space and in engagement with the axially extending tube, the filter element having a filter media, a bottom end cap, a top end cap, and a mounting member defined by the top end cap, the mounting member having an axial wall with a vent passage therethrough and a radial wall that encircles the axial wall. The interface structure is connected to the housing cover and engages the top end cap of the filter element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/884,960, filed on Sep. 17, 2010, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/243,185, filed on Sep. 17,2009, and which also claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/309,171, filed on Mar. 1, 2010.

FIELD OF THE INVENTION

The present invention relates to fluid filter assemblies, and moreparticularly, a fluid filter assembly having a modular interface betweena fluid filter, a housing, and a pressure relief valve.

BACKGROUND OF THE INVENTION

It is well known to utilize fluid filter assemblies to filter fuel for acombustible engine of a motor vehicle. Such fluid filter assembliescomprise a variety of different orientations of the fluid filterassembly. For example, it is known to utilize sideways, downwardly, andupwardly mounted canisters having a paper filter media enclosed in thecanister to form the fluid filter assembly. With respect to upwardlymounted fluid filter assemblies, prior art filtration devices have beenknown to provide fuel to the fluid filter assembly by use of a pump. Thefuel is directed downward into a lower chamber of the fluid filterassembly wherein the fuel flow proceeds upward into an upper filterchamber of the fluid filter assembly. The fuel may then be contained andsealed by a transparent cover or enclosure of the fluid filter assemblyfor viewing the fuel level within the upper filter chamber. A filtermount separates the lower chamber from the upper chamber of the fluidfilter assembly.

Within the filter chamber of the fluid filter assembly, the fluid filterassembly may provide a filter canister comprised of a filter media thatis contained by filter end caps at the top and bottom of the filtermedia. The filter media may, optionally, encircle a central filter tubethat provides additional support for the filter media. The end caps aresealed to the edges of the filter media to preclude any possible leakpaths at the ends of the filter canister. The filter media typicallycomprises a meltblown plastic material or a porous paper material thatmay be pleated or concentrically wound so as to direct the fluid throughthe filter media. The filter media removes undesirable contaminants fromthe fuel by retaining the contaminants within and on the filter media.

As fluid enters the filter chamber, the fuel level rises and passesthrough from the outside to the inside of the filter media. The fuelthen flows downward into a central passage located along the centralaxis of the canister. The central passageway is in communication with afuel outlet wherein the fuel passes outwardly from the fluid filterassembly.

During the filtering process, the fuel is either drawn into the filterchamber by a vacuum created by a pump downstream from the fluid filterassembly, or the fuel may be pushed into the filter chamber by pressurecreated by a pump upstream from the fluid filter assembly. As the fuelflows through the filter media, dirt and other contaminants larger thanthe porous openings in the filter media are trapped and retained by thefilter media. These contaminants plug or clog the porous holes in thefilter media and restrict or close the paths used by the flowing fuel.The fuel is then forced to seek other open and less restrictive flowopenings which are available above the level of the fuel by having thefuel level climb the height of the filter media and access the cleanareas of the filter media. This process of clogging and climbingcontinues until the filter media is completely immersed in the flowingfuel.

Even though the filter media may be completely immersed in the flowingfluid, the incoming fuel continues to pass through the filter media. Itis not until the filter media becomes greatly clogged that the filtercanister needs to be replaced. This is a problem since the usergenerally views the height of the fuel in the filter chamber todetermine if the filter media is clogged. If the filter media iscompletely immersed in fuel, the user generally believes that the filtercanister needs to be replaced. Therefore, this type of system may leadto premature replacement of the filter canister.

It is known that the system described above may be improved upon byproviding a divider and a pressure relief valve on the filter canister.The divider is connected to a top end cap of the filter canister andwraps around the filter media. It functions to divide the portion of thehousing adjacent to the filter media into an inner region that isdefined between the filter media and the divider, and an outer regionthat is defined between the divider and the housing. The divider allowsthe fluid in the inner region to rise fully before the fluid in theouter region begins to rise. The fluid in the outer region rises whenfluid and/or air/vapor passes through the pressure relief valve when thepressure across the filter media exceeds a predetermined pressure. Thepressure relief valve is mounted in an end cap of the filter canister.While this system provides a more accurate indication of the remaininglife of the filter media, the complexity and the cost of the filtercanister is increased over previous designs by its incorporation of adivider and a pressure relief valve. Since the filter canister isroutinely replaced when the filter media becomes clogged, the increasedcost of the filter canister is an undesirable factor in maintaining thefluid filter assembly.

Furthermore, in the systems described above, it is common to mount thefilter upon an outlet pipe that is formed on a base portion of the fluidfilter assembly. The filter is typically biased into engagement with thebase portion and the outlet pipe by using a spring that engages thecover of the fluid filter assembly as well as a top end of the filtercanister. In such systems, the filter cartridge can be installed suchthat it is not perfectly aligned along the filter cartridge axis definedby the outlet pipe of the base portion of the fluid filter assembly,resulting in uneven exposure of the filter media to the fluid within thefluid filter assembly and potentially reducing the accuracy of thevisual indication of remaining life provided by the fluid level withinthe fluid filter assembly.

It would be desirable to provide a fluid filter assembly that providesan accurate indication as to the remaining usefulness of the filtermedia while reducing the complexity and cost of replacing the fuelfilter canister. It would also be desirable to provide a fluid filterassembly that provides for accurate axial alignment within the fluidfilter assembly.

SUMMARY OF THE INVENTION

The invention provides a fluid filter assembly for filtering a fluid.The fluid filter assembly includes an upright housing having a baseportion and a cover that cooperate to define an interior space of theupright housing. The base portion has a fluid inlet for communicatingthe fluid into the upright housing and a fluid outlet for communicatingthe fluid downstream of the upright housing. The cover allows viewing ofthe level of fluid in the upright housing. The fluid filter assemblyalso includes a filter element. An exterior of the filter element is incommunication with the fluid inlet, and an interior of the filterelement is in communication with the fluid outlet. The filter elementhas a filter media for filtering the fluid as it passes from theexterior of the filter element to the interior of the filter element. Abottom end cap of the filter element is connected to the fluid outlet,and a top end cap of the filter element is positioned above the bottomend cap. A mounting member is formed on the top end cap of the filterelement, and a vent passage extends through the mounting member forfluid communication between the interior of the filter element and theexterior of the filter element. The fluid filter assembly furtherincludes an interface structure that is connected to the cover of theupright housing and is removably engageable with the mounting member ofthe filter element.

The fluid filter assembly may include a pressure relief valve that is incommunication with the interior and the exterior of the filter elementfor selectively allowing the fluid and/or air/vapor to pass through thevent passage of the filter element valve when the pressure across thefilter element reaches a predetermined level. The passage of fluidand/or air/vapor through the pressure relief valve raises the level ofthe fluid within the upright housing. The pressure relief valve may beintegrated into the top end cap of the filter element.

The fluid filter assembly may also include an interface structure withan interface housing having an upper interior portion that is incommunication with the exterior of the filter element and a lowerinterior portion that is in communication with the interior of thefilter element and sealed with respect thereto. A pressure relief valveis in communication with the upper interior portion and the lowerinterior portion of the interface housing of the interface structure forselectively allowing the fluid and/or air/vapor to pass through the ventpassage of the filter element valve when the pressure across the filterelement reaches a predetermined level wherein the passage of fluidand/or air/vapor through the pressure relief valve raises the level ofthe fluid within the upright housing.

The interface structure may have a threaded connection with respect tothe cover of the upright housing. The interface structure may alsoinclude an upper portion that is disposed at least partially outside ofthe cover of the upright housing to allow tightening of the threadedconnection of the interface structure with respect to the cover of theupright housing. The interface structure may additionally include alower portion having the threaded portion formed thereon, the lowerportion connected to the upper portion for rotation in unison therewithwhen the torque applied to the upper portion is less than apredetermined torque value and for slipping with respect to the upperportion when the torque applied to the upper portion is greater than apredetermined torque value.

The interface structure may be engageable with the mounting member ofthe filter element to axially align the filter element with respect tothe cover.

The mounting member may include an annular wall that encircles the ventpassage, the annular wall being engageable with the interface structureto axially align the filter element with respect to the cover.

The cover may be at least translucent. Furthermore, the cover may betransparent.

A divider may be positioned adjacent to the exterior of the filtermedia. The divider has an upper end connected to the top end cap of thefilter element and an open lower end that is longitudinally spaced fromthe bottom end cap of the filter element. Thus, at least a portion ofthe filter media located adjacent to the bottom cap is not directlyadjacent to the divider. The divider extends a majority of the distancefrom the top end cap to the bottom end cap.

Alternatively, a divider may be positioned inside the cover of theupright housing adjacent to the cover. The divider has an upper end thatis sealable with respect to the top end cap of the filter media todefine an inner portion of the interior space of the upright housingbetween the divider and filter element and an outer portion of theinterior space of the upright housing between the divider and the cover.The inner and outer portions of the interior space of the uprighthousing may be in fluid communication solely at a bottom end of thedivider. Furthermore, the divider may be fabricated from an opaquematerial to block visibility of the fluid level in the inner portion ofthe interior space of the upright housing.

A further aspect of the disclosed embodiments is a fluid filter assemblyfor filtering a fluid that includes a housing base portion having anaxially extending tube, a housing cover, wherein the housing cover isconnected to the housing base portion to define an interior space, afilter element, and an interface structure. The filter element isdisposed within the interior space and is in engagement with the axiallyextending tube. The filter element has a filter media, a bottom end capconnected to the filter media, a top end cap connected to the filtermedia, and a mounting member defined by the top end cap. The mountingmember has an axial wall with a vent passage therethrough and a radialwall that encircles the axial wall. The interface structure is connectedto the housing cover and has an annular engaging part that defines acentral opening. The interface structure engages the top end cap of thefilter element such that the mounting member of the top end cap isdisposed within the central opening and the annular engaging partencircles the radial wall of the mounting member.

A further aspect of the disclosed embodiments is a fluid filter assemblyfor filtering a fluid that includes a housing base portion having anaxially extending tube, a housing cover having a threaded opening,wherein the housing cover is connected to the housing base portion todefine an interior space, a filter element and an interface structure.The filter element is disposed within the interior space and is inengagement with the axially extending tube. The filter element has afilter media, a bottom end cap connected to the filter media, a top endcap connected to the filter media, and a mounting member defined by thetop end cap. The interface structure has an upper portion that isthreadedly connected to the threaded opening of the housing cover, and alower portion that is engageable with the mounting member of the top endcap of the filter element. The lower portion is connected to the upperportion for rotation in unison therewith when the torque applied to theupper portion is less than a predetermined torque value and for slippingwith respect to the upper portion when the torque applied to the upperportion is greater than a predetermined torque value.

A further aspect of the disclosed embodiments is a fluid filter assemblyfor filtering a fluid that includes a housing base portion having anaxially extending tube, a housing cover, wherein the housing cover isconnected to the housing base portion to define an interior space, afilter element, and a divider. The filter element is disposed within theinterior space and in engagement with the axially extending tube. Thefilter element has a filter media, a bottom end cap connected to thefilter media, and a top end cap connected to the filter media. Thedivider is connected to the housing cover and is positioned inside thehousing cover. The divider has an upper end that is sealable withrespect to the top end cap of the filter media to define an innerportion of the interior space between the divider and filter element andan outer portion of the interior space between the divider and thehousing cover, wherein the divider includes a plurality of spaced-apartribs that connect the divider to the housing cover.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like referenced numerals refer to like parts throughout severalviews and wherein:

FIG. 1 is a schematic drawing showing a fluid filter assembly having avent knob with an integrated relief valve according to a firstembodiment of the present invention;

FIG. 2 is a side view showing a fuel filter for use with the fluidfilter assembly of FIG. 1 of the present invention;

FIG. 3 is a side view showing a vent knob of the fluid filter assemblyof FIG. 1 of the present invention;

FIG. 4 is a sectional view of a pressure relief assembly of the fluidfilter assembly of FIG. 1 of the present invention;

FIG. 5 is a schematic drawing showing a fluid filter assembly having avent knob with an integrated relief valve according to a secondembodiment of the present invention;

FIG. 6 is a side view showing a fuel filter for use with the fluidfilter assembly of FIG. 5 of the present invention;

FIG. 7 is a side view of a pressure relief assembly of the fluid filterassembly of FIG. 5 of the present invention;

FIG. 8 is a schematic drawing showing a fluid filter assembly of thepresent invention having a cover with an integral divider;

FIG. 9 is a top view of the divider of the fluid filter assembly of FIG.8 of the present invention;

FIG. 10 is a schematic drawing showing a fluid filter assembly of thepresent invention for use with a fuel filter having a cylindricalmounting member, wherein the fuel filter has an integrated relief valve;

FIG. 11 is a schematic drawing showing a fluid filter assembly of thepresent invention for use with a fuel filter having a cylindricalmounting portion, wherein the fluid filter assembly includes a vent knobhaving an integrated relief valve;

FIG. 12 is a sectional view showing a fluid filter assembly of thepresent invention having a modular fluid filter interface;

FIG. 13 is a perspective view showing the modular fluid filter interfaceof FIG. 12;

FIG. 14 is a perspective view showing a vent knob of the modular fluidfilter interface of FIG. 12;

FIG. 15 is a sectional view showing an upper portion of the vent knob ofFIG. 14;

FIG. 16 is a sectional view showing a lower portion of the vent knob ofFIG. 14;

FIG. 17 is a perspective view showing an interface seal of the modularfluid filter interface of FIG. 12;

FIG. 18 is a perspective view showing an interface portion of a filtercartridge of the modular fluid filter interface of FIG. 12;

FIG. 19 is a perspective view of a modular fluid filter interfaceaccording to a second embodiment;

FIG. 20 is a perspective view showing an interface portion of a fuelfilter cartridge of the modular fluid filter interface of FIG. 19;

FIG. 21 is a sectional view showing a vent knob having an interface ringthat is located on an axial end face of the vent knob; and

FIG. 22 is a sectional detail view of a fluid filter assembly, wherein asealing ring is recessed with respect to a cover of the fluid filterassembly.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to the drawings, the present invention will now be describedin detail with reference to the preferred embodiment.

FIGS. 1-4 show a fluid filter assembly 10 according to the presentinvention. The fluid filter assembly 10 includes a fluid filter 12having a filter element 14 for filtering and processing fluidsincluding, but not limited to, diesel fuel, gasoline, oil, water, air,and antifreeze. The fluid filter assembly 10 includes a substantiallycylindrical, upright housing 2 that is connected to a base portion 3that defines an interior space 4 of the fluid filter assembly 10.Preferably, the upright housing 2 is oriented vertically. The fluidfilter assembly 10 is adapted to receive the fluid filter 12 within theinterior space 4. The fluid filter assembly 10 also has a pressurerelief structure 50 separate from the fluid filter 12, that opens whenthe pressure level across the filter element 14 reaches a predeterminedlevel, thereby allowing fluid and/or air/vapor to pass through thepressure relief structure 50 and allowing the level of fluid to risewithin the fluid filter assembly 10. The pressure relief structure 50acts as an interface between the fluid filter 12 and the upright housing2. Because the pressure relief structure 50 is separate from the fluidfilter 12 of the fluid filter assembly 10, the cost of replacing aclogged fluid filter 12 is substantially reduced compared to a fluidfilter having a built-in pressure relief valve.

The upright housing 2 of the fluid filter assembly 10 is typicallyfabricated from a transparent or translucent material so that the levelof the fluid in the interior space 4 of the upright housing 2 may beviewed from the exterior of the fluid filter assembly 10. The uprighthousing 2 is hollow and generally cylindrical, having side walls 7 and asubstantially semi-spherical domed top portion 8. A threaded bore 9 isformed through the substantially semi-spherical domed top portion 8, anda complementarily threaded vent cap 44 is receivable within the threadedbore 9 to equalize the air pressure within the interior space 4 of thefluid filter assembly 10 with atmospheric pressure to facilitateinstallation and removal of the upright housing 2 with respect to thebase portion 3. The threaded bore 9 is in substantial alignment with alongitudinal axis of the upright housing 2. In order to seal thethreaded vent cap 44 with respect to the upright housing 2, a sealingring 43 encircles the threaded vent cap 44 and is disposed between thethreaded vent cap 44 and the semi-spherical domed top portion 8 of theupright housing 2.

A fluid inlet 5 is formed in the base portion 3 and is adapted to supplyfluid into the enclosed interior space 4 for contact of the fluid withthe filter element 14 of the fluid filter 12. A fluid outlet 6 includesa tube-like member formed near the center of the base portion 3 so thatthe fluid outlet 6 may extend into the fluid filter assembly 10 toreceive and direct filtered fluid outwardly away from the fluid filterassembly 10. In the foregoing, the fluid filter assembly 10 is describedas an outside to inside fluid filter assembly 10, wherein fluid isfiltered by moving from the exterior of the fluid filter 12 to theinterior of the fluid filter 12. However, it should be understood thatthe fluid filter assembly 10 could also be utilized in a filteringprocess where fluid is filtered in an inside-to-outside manner, whereinfluid is filtered by moving the fluid from the interior of the fluidfilter 12 to the exterior of the fluid filter 12, in which case, theroles of the fluid inlet 5 and the fluid outlet 6 would be reversed.

To filter contaminants from the fluid, the fluid filter 12 includes afilter element 14. The filter element 14 is fabricated from a porous,fluid permeable material that is adapted to trap contaminants. As anexample, the filter element 14 may be fabricated from a meltblownplastic material or a paper material. The filter element 14 encircles acentral filter tube 16 and is contained by a top end cap 18 and a bottomend cap 20, respectively. However, the central filter tube 16 isoptional and could be omitted. The top and bottom end caps 18, 20 aresealed to the edges of the filter element 14 to preclude any possibleleak paths at the ends of the filter element 14. A flexible seal 22 isprovided on the bottom end cap 20 of the filter element 14 to create aseal between the fluid outlet 6 and the bottom end cap 20 of the filterelement 14 and ensure that unfiltered fluid does not leak into or escapethrough the fluid outlet 6. The filter element 14 is preferably pleatedor concentrically wound but may also be arranged in any of the waysknown to one familiar with filtration construction so as to direct thefluid through the filter element 14. In addition, the filter element 14may be fabricated from a hydrophobic filter material to filter out waterfrom the fluid.

In order to connect the fluid filter 12 to the pressure relief structure50, an upstanding nozzle 26 is formed on the top end cap 18 of the fluidfilter 12. The nozzle 26 typically extends along a longitudinal axis ofthe fluid filter 12 and is surrounded by a substantially circular trough28 that is formed on the top end cap 18. In order to allow fluidcommunication between the inner core 24 of the fluid filter 12 and thepressure relief structure 50, a passageway 30 extends through the nozzle26 so that the air/vapor pressure on each end of the nozzle 26 isequalized.

The fluid filter 12 may include a fluid impervious divider 32 thatdivides the interior space 4 of the upright housing 2 between the fluidfilter 12 and the sidewall 7 of the upright housing 2. The divider 32has a top portion 34 that is either integrally or sealingly connected tothe top end cap 18 of the fluid filter 12. The divider 32 issubstantially cylindrical, such that a bottom portion 36 of the divider32 extends downward substantially parallel to the filter element 14. Itshould be noted, however, that the present invention is not limited tothe cylindrical divider 32, but rather, the divider 32 may also besubstantially frustroconical, wherein the divider 32 tapers outwardlyfrom the filter element 14 such that the bottom portion 36 of thedivider 32 is spaced from the filter element 14. In both embodiments,the divider 32 essentially divides the interior space 4 of the uprighthousing 2 into an inner portion 38 and an outer portion 40. The innerportion 38 is the space contained between the outside or unfiltered sideof the filter element 14 and the inner surface of the divider 32. Theouter portion 40 is the space contained between the outer surface of thedivider 32 and the inner surface of the sidewall 7 of the uprighthousing 2. The inner and outer portions 38, 40 remain in fluidcommunication at the bottom of the upright housing 2.

In order to secure the fluid filter 12 with respect to the base portion3, a compression spring 42 at the top of the upright housing 2 engagesthe fluid filter 12 to maintain the fluid filter 12 in a sealedrelationship with the base portion 3. The spring 42 is seated on ashoulder 11 formed on the interior of the upright housing 2 around thethreaded bore 9. The opposite end of the spring 42 is seated in thecircular trough 28 formed in the top end cap 18 of the fluid filter 12.The circular trough 28 functions to maintain an upright axial alignmentof the fluid filter 12 within the upright housing 2 but could beomitted.

As best seen in FIGS. 3 and 4, the pressure relief structure 50 includesa housing 52 having an upper end 54 and a lower end 56. A connectingstructure, such as an annular lip or a plurality of fingers 58, isprovided at the upper end 54 of the housing 52 to engage a groove 46 orsimilar structure provided on the vent cap 44 in order to connect thehousing 52 of the pressure relief structure 50 to the vent cap 44. Itwill be understood that the housing 52 could be connected to the ventcap 44 by other means, such as adhesives or sonic welding; in whichcase, the fingers 58 and the groove 46 would be unnecessary. Inaddition, the housing 52 could be integrally formed with the vent cap44.

In order to connect the housing 52 to the fluid filter 12, a filterinterface passage 55 is formed through the housing 52 at the lower end56 thereof. A sealing means, such as a gasket 57, may be provided withinthe filter interface passage 55 to provide a sealed connection of thepressure relief structure 50 with the fluid filter 12. The gasket 57 isannular, such that it may surround the nozzle 26 of the fluid filter 12and may be substantially tubular, have a C-shaped cross-section, orotherwise be configured to provide a seal with respect to the nozzle 26,as seen in FIGS. 1 and 4.

The housing 52 has a hollow interior 59, 60 that is bifurcated by adivider plate 62. In particular, the divider plate 62 divides the hollowinterior 59, 60 of the housing 52 into an upper interior portion 59 anda lower interior portion 60. An aperture 64 extends through the dividerplate 62 for fluid communication between the upper interior portion 59and the lower interior portion 60. The upper interior portion 59 is influid communication with the interior space 4 of the upright housing 2of the fluid filter assembly 10 by way of vent ports 66 that extendthrough the housing 52 near the upper end 54 of the housing 52. Thelower interior portion 60 is in fluid communication with the inner core24 of the fluid filter 12 through the filter interface passage 55.

In order to selectively establish fluid communication between the upperand lower interior portions 59, 60 of the housing 52, a normally closed,pressure sensitive valve 68 is disposed within the aperture 64 thatextends through the divider plate 62 or may be seated within a separateaperture. The air/vapor pressure acting on an upper side 70 of thepressure sensitive valve 68 is the air/vapor pressure in the interiorspace 4 of the fluid filter assembly 10, while the pressure acting on alower side 72 of the pressure sensitive valve 68 is the pressure withinthe inner core 24 of the fluid filter 12. When the pressure across thepressure sensitive valve 68 reaches a predetermined pressure, thepressure sensitive valve 68 moves from a closed position to an openposition. The pressure sensitive valve 68 opens by disengaging from atleast a portion of the aperture 64. When the pressure sensitive valve 68is in the open position, gases, vapors, and/or liquids are allowed topass through the aperture 64 from the upper interior portion 59 to thelower interior portion 60 of the housing 52 of the pressure reliefstructure 50.

The fluid filter assembly 10 of FIG. 1 is adapted to be utilized inconjunction with the spring 42, which biases the fluid filter 12downward onto the fluid outlet 6 so that the fluid filter 12 engages thebase portion 3. Any variation of the vertical position of the fluidfilter 12 with respect to the pressure relief structure 50 isaccommodated by the length of the nozzle 26 of the fluid filter 12, inthat the degree of insertion of the nozzle 26 into the filter interfacepassage 55 and gasket 57 may vary according to the vertical position ofthe fluid filter 12 with respect to the pressure relief structure 50.However, it will be understood that the spring 42 could be omitted.

In operation, fluid enters the fluid inlet 5 of the fluid filterassembly 10 of FIG. 1 and accumulates within the interior space 4defined by the base portion 3 and the upright housing 2 of the fluidfilter assembly 10. By employing the divider 32 and the pressure reliefstructure 50, the fluid level can be made to rise approximately inproportion to the plugging rate of the filter element 14. This gives anaccurate visual indicator as to the remaining life of the filter element14.

When the fluid level approaches the bottom portion 36 of the divider 32,the fluid continues to rise in the area between the filter element 14and the inner surface of the divider 32, which was previously defined asthe inner portion 38 of the interior space 4 of the upright housing 2.However, the fluid does not initially rise between the outer surface ofthe divider 32 and the side wall 7 of the upright housing 2, which waspreviously defined as the outer portion 40 of the interior space 4 ofthe upright housing 2. This is because trapped air/vapor prevents therise of fluid in the outer portion 40 of the interior space 4 of theupright housing 2.

As to the inner portion 38 of the upright housing 2, fluid and air/vapormove through the filter element 14 of the fluid filter 12 in a usualmanner. The fluid level continues to rise between the filter element 14and the inside surface of the divider 32 as the filter element 14becomes more clogged. This continues until the fluid has risen to thefull or nearly full height of the filter element 14, as previouslydescribed. Once this occurs, the pressure differential across the filterelement 14 begins to increase with the increased clogging of the filterelement 14. Once this pressure differential reaches a predeterminedlevel, the pressure sensitive valve 68 of the pressure relief structure50 may open to allow vapor/air to flow through the pressure sensitivevalve 68. Thus, when the pressure differential across the filter element14 exceeds the predetermined pressure differential level, the pressurerelief structure 50 becomes the preferred flow path since its pressuredifferential is fixed. By way of non-limiting example, the predeterminedpressure differential could be a predetermined pressure differential inthe range of 3-6″ Hg. Since air/vapor is closest to the pressure reliefstructure 50, the air/vapor flows through the pressure sensitive valve68 of the pressure relief structure 50 first. As the fluid level beginsto rise in the outer portion 40 of the interior space 4 of the uprighthousing 2, the fluid level provides a visual indicator to the operatoras to when the filter element 14 should be replaced. Once the user seesthat the fluid level in the outer portion 40 of the upright housing 2has risen to the top of the fluid filter 12, the user knows to replacethe fluid filter 12. After the fluid level rises above the vent ports 66of the pressure relief structure 50, fluid may also flow through thepressure sensitive valve 68 along with the air/vapor. Again, by nothaving the pressure sensitive valve 68 built into the fluid filter 12,the cost of replacing the fluid filter 12 is reduced, as the pressuresensitive valve 68 need not be replaced.

FIGS. 5-7 show a second embodiment of the fluid filter assembly 10,which includes an alternative pressure relief structure 150. Thepressure relief structure 150 is similar to the pressure reliefstructure 50 described in connection with FIG. 1, except as notedherein. So that the pressure relief structure 150 may urge the fluidfilter 12 into engagement with the base portion 3 of the fluid filterassembly 10, the length of a housing 152 of the pressure reliefstructure 150 is selected to completely occupy the vertical spacebetween the vent cap 44 and the top end cap 18 of the fluid filter 12when the fluid filter 12 is firmly seated upon the base portion 3. Inorder to provide a seal between the housing 152 of the pressure reliefstructure 150 and the fluid filter 12, an annular face seal 157 isprovided on a lower end 156 of the housing 152 and extends into a filterinterface passage 155 of the housing 152. The annular face seal 157 isconfigured to be received within the circular trough 28 that extendsaround the nozzle 26 of the fluid filter 12 such that the annular faceseal 157 sealingly engages the end cap of the fluid filter 12. Notably,the embodiment shown in FIGS. 5-7 does not require a compression springto urge the fluid filter 12 into engagement with the base portion 3.

Operation of the embodiment of the fluid filter assembly 10 of FIG. 5 isidentical to that of the fluid filter assembly 10 of FIG. 1.

FIG. 8 shows a third embodiment of the fluid filter assembly 10, whereina fluid filter assembly 200 having a divider 232 is connected to orformed integrally with an upright housing 202 thereof. The fluid filterassembly 200 may be used in conjunction with a pressure relief structure50, as shown in FIG. 1, a pressure relief structure 150, as shown inFIG. 5, or with a pressure relief structure 50 that is provided as aportion of the fluid filter 12.

As best seen in FIGS. 8 and 9, the divider 232 is generally cylindricalin shape, having a sidewall 242 that creates a generally tubular shapefor the divider 232 below an axial end cap 244 of the divider 232. Acentral aperture 246 is defined through the axial end cap 244. Anannular sealing ring 248 surrounds the central aperture 246 and islocated on the interior of the divider 232 in order to create a sealbetween the divider 232 and the fluid filter 12. A plurality of ribs 250are arrayed circumferentially around the sidewall 242 and axial end cap244 of the divider 232 in order to strengthen the divider 232 and spacethe sidewall 242 from the upright housing 202. The ribs 250 may engagethe upright housing 202 in a friction fit. The divider 232 may beultrasonically welded to the upright housing 202, for example, adjacentto the central aperture 246. Alternatively, the divider 232 could befabricated integrally with the upright housing 202. The upright housing202 and the divider 232 may be fabricated from a plastic material.

The divider 232 divides the interior space 4 within the upright housing202 into an interior portion 238 that is disposed between the divider232 and the fluid filter 12 and an exterior portion 240 that is disposedbetween the upright housing 202 and the divider 232. The interiorportion 238 and the exterior portion 240 are in fluid communication atthe bottom edge of the sidewall 242 of the divider 232. The annularsealing ring 248 prevents fluid communication between the interiorportion 238 and the exterior portion 240 at the top of the divider 232.Preferably, the divider 232 is opaque, while at least a portion of theupright housing 202 is transparent or translucent. In this manner, thefluid level within the exterior portion 240 of the interior space isvisible from outside the fluid filter assembly 200, while the fluidlevel in the interior portion 238 is not visible.

Operation of the divider 232 during filtering of the fluid is asdescribed in connection with the divider 32 of the fluid filter assembly10 of FIG. 1.

According to a further embodiment of the invention, FIG. 10 shows afluid filter assembly 310. The fluid filter assembly 310 includes afluid filter 312 having a substantially cylindrical mounting member 314and an integral pressure sensitive valve 316 provided on or within thecylindrical mounting member 314. The fluid filter assembly 310 alsoincludes a connecting structure 350 that is connected to or formedintegral with the vent cap 44, which is as described in connection withthe embodiment of FIG. 1, for use with an upright housing 2 (shown inFIG. 1) of the fluid filter assembly 310. The connecting structure 350is engageable with the cylindrical mounting member 314 of the fluidfilter 312 to stabilize the fluid filter 312 axially within the uprighthousing 2.

The cylindrical mounting member 314 of the fluid filter 312 is disposedalong a longitudinal axis of the fluid filter 312 and extends upwardfrom a top end cap 318 of the fluid filter 312. An arcuate,substantially circular trough 320 may be formed on the top end cap 318around the cylindrical mounting member 314. The cylindrical mountingmember 314 extends from the arcuate trough 320 or from the top end cap318 to an upper axial wall 322 of the cylindrical mounting member 314.In order to allow the passage of air/vapor and/or fluids into theinterior of the fluid filter 312, an aperture 324 is formed through theupper axial wall 322 of the cylindrical mounting member 314 and may bedisposed along the longitudinal axis of the fluid filter 312.

In order to control the passage of air/vapor and/or fluids into thefluid filter 312 through the aperture 324 in the cylindrical mountingmember 314, the pressure sensitive valve 316 is mounted in the aperture324 or within a separate aperture that is adjacent to the aperture 324to selectively establish or prevent fluid communication into theinterior of the fluid filter 312 through the aperture 324. Operation ofthe pressure sensitive valve 316 is identical to that described inconnection with the pressure sensitive valve 68 of the embodiment ofFIG. 1. In particular, the pressure sensitive valve 316 allows passageof air/vapor and/or fluids through the aperture 324 at or above apredetermined pressure. Although the present invention is ideally suitedfor the pressure sensitive valve 316 to be fabricated from a pressuresensitive rubber valve member, the pressure sensitive valve 316 may beprovided in the form of any valve structure operable to perform thisfunction, including check ball valves or restricted filtration mediathat prevents the passage of air/vapor and/or fluids below thepredetermined pressure.

The connecting structure 350 of the fluid filter assembly 310 is anopen-ended substantially cylindrical structure having an interiordiameter that corresponds to the exterior diameter of the cylindricalmounting member 314 of the fluid filter 312. In particular, theconnecting structure 350 includes a cylindrical wall 352 that isconnected to or formed integrally with the vent cap 44. The cylindricalwall 352 defines an open end 354 opposite the vent cap 44. Vent passages356 are formed through the cylindrical wall 352 of the connectingstructure 350 adjacent to the vent cap 44 in order to allow fluidcommunication between the interior of the upright housing 2 and aninterior space 358 that is defined within the cylindrical wall 352. Whenthe connecting structure 350 is seated on the cylindrical mountingmember 314, the interior space 358 is in fluid communication with thepressure sensitive valve 316.

In order to connect and seal the connecting structure 350 with respectto the cylindrical mounting member 314 of the fluid filter 312, asealing member 360 is provided on the cylindrical wall 352 of theconnecting structure 350. The sealing member 360 may be fabricated fromany suitable gasket material, such as rubber. The sealing member 360 maybe disposed on the cylindrical wall 352 at the open end 354 thereof,and/or on an interior surface 362 of the cylindrical wall 352.

Operation of the fluid filter assembly 310 is as described in connectionwith the fluid filter assembly 10 of FIG. 1.

As shown in FIG. 11, a fluid filter assembly 410 according to a furtherembodiment of the invention includes a fluid filter 412 having acylindrical mounting member 414 for engagement with a connectingstructure 450 that has a pressure sensitive valve 468 disposed therein.The fluid filter 412 and the cylindrical mounting member 414 areidentical to the fluid filter 312 and cylindrical mounting member 314described in connection with FIG. 10, with the exception that the fluidfilter 412 does not have a pressure sensitive valve disposed therein.

The connecting structure 450 is similar to the connecting structure 350described in connection with FIG. 10, and thus includes a cylindricalwall 452 having an open end 454 and vent passages 456. However, theconnecting structure 450 differs from that shown and described inconnection with FIG. 10 by inclusion of the pressure sensitive valve 468therein.

In order to provide the pressure sensitive valve 468 in the connectingstructure 450, a divider 464 is disposed within the connecting structure450 and is a disc-like structure that is oriented substantiallyperpendicular to the longitudinal axis of the connecting structure 450.Accordingly, the divider 464 cooperates with the cylindrical wall 452 ofthe connecting structure 450 to define an upper interior space 466 and alower interior space 467 of the connecting structure 450. The upperinterior space 466 of the connecting structure 450 is in fluidcommunication with the vent passages 456. The lower interior space 467of the connecting structure 450 is adjacent to the open end 454 definedby the cylindrical wall 452 of the connecting structure 450 such thatthe lower interior space 467 of the connecting structure 450 is in fluidcommunication with an aperture 424 formed through an axial end wall 422of the cylindrical mounting member 414 of the fluid filter 412. Thus,air/vapor and/or fluids are able to enter the interior of the fluidfilter 412 through the aperture 424 from the lower interior space 467 ofthe connecting structure 450.

In order to selectively establish and prevent fluid communicationbetween the upper interior space 466 and the lower interior space 467 ofthe connecting structure 450, an aperture 470 is formed through thedivider 464, and the pressure sensitive valve 468 is disposed within theaperture 470 or within an additional aperture. The pressure sensitivevalve 468 of the connecting structure 450 is identical in structure andfunction to the pressure sensitive valve 68 described in connection withFIG. 1. Accordingly, air/vapor and/or fluids may pass the pressuresensitive valve 468 at or above the predetermined pressure.

Operation of the fluid filter assembly 410 is as described in connectionwith the fluid filter assembly 10 of FIGS. 1-4.

FIGS. 12-13 show a fluid filter assembly 510 having a modular fluidfilter interface. The fluid filter assembly 510 includes a fluid filter512 having a substantially cylindrical mounting member 514 that isformed on a top end cap 518 of the fluid filter 512. An integralpressure sensitive valve 516 is provided on or within the cylindricalmounting member 514. The fluid filter assembly 510 also includes aconnecting structure 550 that is connected to or formed integral with avent cap 540. The vent cap 540 is threadedly connected to the threadedbore 9 of the upright housing 2, which is as described in connectionwith the embodiment of FIG. 1. The connecting structure 550 isengageable with the cylindrical mounting member 514 of the fluid filter512 to stabilize the fluid filter 512 within the upright housing 2.

As shown in FIG. 14, the vent cap 540 has an upper portion 560 and alower portion 570. The upper portion 560 of the vent cap 540 has acontoured outer periphery 562 that is engageable with the fingers of auser to allow the user to tighten and loosen the vent cap 540 byrotating the vent cap 540 with respect to the upright housing 2 of thefluid filter assembly 510. The lower portion 570 of the vent cap 540 issubstantially cylindrical and includes a threaded portion 571 on itsouter periphery. The threaded portion 571 of the lower portion 570 ofthe vent cap 540 is engageable with the threaded bore 9 of the uprighthousing 2 in order to secure the vent cap 540 with respect to theupright housing 2. An interface ring 580 may be disposed within a lowercavity 572 of the lower portion 570 of the vent cap 540, which is formedopposite the upper portion 560 of the vent cap 540. The lower cavity 572and the interface ring 580 are portions of the connecting structure 550,as will be explained in detail herein.

The upper portion of the vent cap 540 includes an axial end wall 564that is bounded by the contoured outer periphery 562, as seen in FIG.15. A plurality of hook-like retainers 566 extend downward from theaxial end wall 564 in a circular array around a longitudinal axis 561 ofthe upper portion 560. Each of the hook-like retainers 566 is spacedinward from the contoured outer periphery 562 of the upper portion 560of the vent cap 540. The retainers 566 exhibit some resiliency withrespect to the axial end wall 564. Inward from the hook-like retainers566, a pair of arcuate fingers 568 extend downward from the axial endwall 564, which also exhibit some resiliency with respect to the axialend wall 564. The arcuate fingers 568 are opposed from one another sothat a spring 565 (FIG. 12) can be received between the arcuate fingers568 to bias the arcuate fingers 568 away from one another. A pluralityof longitudinally-extending triangular ridges 569 are formed on theouter surfaces of the arcuate fingers 568. The triangular ridges 569 maybe asymmetrical, such that the triangular ridges 569 are capable offunctioning as one-way camming structures, as will be explained indetail herein.

The lower portion 570 of the vent cap 540 is substantially cylindricaland defines the lower cavity 572, as well as an upper cavity 574, asseen in FIG. 16. A circumferential groove 575 is defined on the outerperiphery of the lower portion 570 above the threaded portion 571. Thecircumferential groove 575 is engageable with the retainers 566 of theupper portion 560 of the vent cap 540 to releasably secure the upperportion 560 with respect to the lower portion 570. The engagementbetween the circumferential groove 575 and the retainers 566 does notresist rotation of the upper portion 560 with respect to the lowerportion 570.

Within the upper cavity 574 of the lower portion 570, a plurality ofridges 576 are formed on the lower portion 570 and arrayed around theinterior of the upper cavity 574. The ridges 576 extend axially and areengageable with the triangular sides 569 of the upper portion 560.Engagement of the triangular sides 569 of the upper portion 560 with theridges 576 of the lower portion 570 serves to restrain rotation of theupper portion 560 with respect to the lower portion 570. Due to theasymmetric nature of the triangular sides 569, engagement of thetriangular sides 569 with the ridges 576 in a first direction serves torotate the upper portion 560 and the lower portion 570 in unisonregardless of the magnitude of torque applied. In a second direction,the triangular sides 569 are inclined such that engagement of the ridges576 with the triangular sides 569 will displace the arcuate fingers 568of the upper portion 560 inward slightly to allow the triangular sides569 to rotate past the ridges 576 when the torque applied to the ventcap 540 exceeds a predetermined amount. The magnitude of torque requiredto allow the upper portion 560 of the vent cap 540 to rotate withrespect to the lower portion 570 is determined by the stiffness of thespring 565, which resists deflection of the arcuate fingers 568 towardone another, as well as by the force required to deflect the arcuatefingers 568 themselves.

In order to provide a tolerance stack-up compensator between the ventcap 540 and the fluid filter 512, the interface ring 580 is disposed inthe lower cavity 572 of the lower portion 570 of the vent cap 540. Inparticular, the interface ring 580 is seated on a shoulder 578 that isformed on the lower portion 570 of the vent cap 540 within the lowercavity 572. As shown in FIG. 17, the interface ring 580 is circular butincludes a plurality of radially-extending passages 582 that extendcompletely through the interface ring 580 in the radial direction butwhich extend approximately halfway through the interface ring 580 in anaxial direction, such that the passages 582 are open at one axial end ofthe interface ring 580.

As shown in FIG. 18, the substantially cylindrical mounting member 514of the fluid filter 512 is disposed along a longitudinal axis of thefluid filter 512 and extends upward from the top end cap 518 of thefluid filter 512. A trough 520 may be formed on the top end cap 518around the cylindrical mounting member 514 and encircles the cylindricalmounting member 514. A radial wall 521 extends from the trough 520 to anupper axial wall 522 of the cylindrical mounting member 514. In order toallow the passage of air/vapor and/or fluids into the interior of thefluid filter 512, a plurality of axially-extending troughs 525 arearrayed around the radial wall 521 of the cylindrical mounting member514. The relative elevations of the trough 520, the upper axial wall 522of the substantially cylindrical mounting member, and the nominalelevation of the remainder of the top end cap 518 cooperate to trap atleast a portion of the sediment that may be present within the fluidwithin the trough 520. In particular, the trough 520 is disposed at anelevation that is below the remainder of the top end cap 518. The upperaxial wall 522 is disposed at an elevation that is above both the topend cap 518 and the trough 520. Thus, as fluid flows over the top endcap, it necessarily enters the trough 520 before traveling through theaxially-extending troughs 525 on the radial wall 521 and past thepressure sensitive valve 516, as will be explained herein. While thefluid is disposed within the trough 520, gravity operates to retain thesediment within the trough 520.

The pressure sensitive valve 516 is seated within an aperture 517 thatis formed through the upper axial wall 522 of the cylindrical mountingmember 514. The aperture 517 and the pressure sensitive valve 516 aresurrounded by a pair of arcuate walls 523 that extend upward from theupper axial wall 522. The arcuate walls 523 oppose one another and arespaced with respect to one another by a pair of gaps 526. The arcuatewalls 523 extend upward from the upper axial wall 522 of the cylindricalmounting member 514 at a height that is greater than the height at whichthe pressure sensitive valve 516 extends outward from the upper axialwall 522 of the cylindrical mounting member 514. Accordingly, thearcuate walls 523 provide protection to the pressure sensitive valve 516both prior to and after installation, while fluid flow is accommodatedthrough the gaps 526.

The pressure sensitive valve 516 functions to selectively establish orprevent fluid communication into the interior of the fluid filter 512through the aperture 517. Operation of the pressure sensitive valve 516is identical to that described in connection with the pressure sensitivevalve 68 of the embodiment described in connection with FIG. 1.

In operation, the fluid filter 512 is disposed within the uprighthousing 2, and the vent cap 540 is threadedly connected to the uprighthousing 2 by engagement of the threaded bore 9 of the upright housing 2with the threaded portion 571 of the lower portion 570 of the vent cap540. As the vent cap 540 is engaged with the upright housing 2, thesubstantially cylindrical mounting member 514 of the fluid filter 512enters the lower cavity 572 of the lower portion 570 of the vent cap540. As the vent cap 540 becomes fully seated with respect to the fluidfilter 512, the radial wall 521 of the substantially cylindricalmounting member 514 engages the lower portion 570 of the vent cap 540,and the arcuate walls 523 extend past the shoulder 578 within the lowercavity 572 of the lower portion 570 of the vent cap 540. The interfacering 580 then engages both the upper axial wall 522 of the substantiallycylindrical mounting member 514 of the fluid filter 512, as well as theshoulder 578 of the lower portion 570 of the vent cap 540. Thisengagement creates a partial seal between the connecting structure 550of the vent cap 540 and the substantially cylindrical mounting member514. When fully seated with respect to the fluid filter 512, theaxially-extending troughs 525 of the substantially cylindrical mountingmember 514 come into alignment with the radially-extending passages 582in the interface ring 580.

With the vent cap 540 fully seated upon the fluid filter 512, the usermay begin filtration of the fluid. Once the fluid filter 512 becomessignificantly clogged, air/vapor/fluid enters the trough 520 thatextends around the substantially cylindrical mounting member 514 andproceeds through the axially-extending troughs 525 on the radial wall521 as the fluid level rises until the fluid passes through theradially-extending passages 582 of the interface ring 580 and thenthrough the gaps 526 between the arcuate walls 523. Then, when thepredetermined pressure is exceeded, the fluid may pass the pressuresensitive valve 516 and into the fluid filter 512.

FIGS. 19-20 show a fluid filter assembly 610 having an alternativemodular fluid filter interface for use with the vent cap 540. The fluidfilter assembly 610 is identical to the fluid filter assembly 510 withthe exception that a fluid filter 612 of the fluid filter assembly 610includes a substantially cylindrical mounting member 614 having asubstantially flat axial end wall 622. The arcuate walls 523, asdescribed in connection with the fluid filter 512, are omitted. Thus, apressure sensitive valve 616, which is seated in an aperture 617, is theonly structure that extends outward from the axial end wall 622 of thecylindrical mounting member 614.

Operation of the fluid filter assembly 610 is as described in connectionwith the fluid filter assembly 510 with the exception that the fluidneed not pass through the gaps 526 between the arcuate walls 523 due toomission of the arcuate walls 523.

In an alternative embodiment, as shown in FIG. 21, the fluid filterassembly 510 of FIG. 12 may be provided with a vent knob 740 wherein aninterface ring 780 is positioned in a groove 742 that is located on anaxial end face 744 of the vent knob 740. The interface ring 780 includesradially extending passages 782 and is similar in structure and functionto the interface ring 580. When the vent knob 740 is installed withrespect to the fluid filter 512, the groove 742 is positioned oppositethe trough 520 of the fluid filter 512, such that the interface ring 780is engaged with the vent knob 740 and the top end cap 518 of the fluidfilter 512. As explained in connection with the interface ring 580,fluid may flow to the pressure sensitive valve 516 by way of theradially extending passages 582, and thus, operation is as described inconnection with the fluid filter assembly 510. Of course, the vent knob740 could also be used in conjunction with the fluid filter assembly 610of FIG. 19.

In another alternative embodiment, as shown in FIG. 22, a fluid filterassembly 810 includes an upright housing 802 having a recess 812. Therecess 812 is formed in a spherical domed top portion 808 of the uprighthousing 802, adjacent and concentric to a threaded bore 809 that isformed through the substantially semi-spherical domed top portion 808. Avent cap 840 of the fluid filter assembly 810 includes a sealing ring842 that is seated in an annular groove 844. The annular groove 844 isformed above a threaded stem portion 846 of the vent cap 840 and below aknob portion 848 of the vent cap 840. When the vent cap 840 is installedwith respect to the upright housing 802, the sealing ring is disposedwithin the recess 812 and in engagement with the upright housing 802.The structure of the upright housing 802 and the vent cap 840 may beincorporated in any of the previous embodiments, and operation is asdescribed in connection with those embodiments.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, it is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims, the scope is to be accorded thebroadest interpretation so as to encompass all such modifications andequivalent structures as is permitted under the law.

What is claimed is:
 1. A fluid filter assembly for filtering a fluid,comprising: a housing base portion having an axially extending tube; ahousing cover, wherein the housing cover is connected to the housingbase portion to define an interior space; a filter element disposedwithin the interior space and in engagement with the axially extendingtube, the filter element having a filter media, a bottom end capconnected to the filter media, a top end cap connected to the filtermedia, and a mounting member defined by the top end cap, the mountingmember having an axial wall with a vent passage therethrough and aradial wall that encircles the vent passage; and an interface structurethat is connected to the housing cover and serves as an interfacebetween the interior space and the filter element, the interfacestructure having an annular engaging part that defines a centralopening, wherein the interface structure engages the top end cap of thefilter element such that the vent passage of the mounting member isdisposed within the central opening of the interface structure to createa fluid communication channel between the central opening, the ventpassage, and the axially extending tube.
 2. The fluid filter assembly ofclaim 1, wherein the housing cover defines a threaded opening, theinterface structure includes a threaded portion, and the interfacestructure is connected to the housing cover by threaded engagement ofthe threaded opening of the housing cover with respect to the threadedportion of the interface structure.
 3. The fluid filter assembly ofclaim 2, wherein the interface structure includes a knob portion that isdisposed outside of the housing cover.
 4. The fluid filter assembly ofclaim 1, wherein the interface structure engages the top end cap of thefilter element via a non-threaded engagement.
 5. The fluid filterassembly of claim 1, wherein the annular engaging part of the interfacestructure is in engagement with the top end cap of the filter element.6. The fluid filter assembly of claim 1, wherein engagement of thefilter element and the annular engaging part of the interface structureurges the filter element into engagement with the housing base portion.7. The fluid filter assembly of claim 1, wherein the interface structureincludes an annular sealing member that is in engagement with the topend cap of the filter element.
 8. The fluid filter assembly of claim 1,wherein the top end cap includes a base surface that encircles themounting member, and the annular engaging part of the interfacestructure is in engagement with the base surface of the top end cap. 9.The fluid filter assembly of claim 1, wherein the top end cap includes atrough that encircles the mounting member, and the annular engaging partof the interface structure is in engagement with the trough of the topend cap.
 10. The fluid filter assembly of claim 1, further comprising: apressure relief valve disposed in the vent passage of the mountingmember of the top end cap of the filter element.
 11. The fluid filterassembly of claim 1, further comprising: a pressure relief valvedisposed in the interface structure for selectively preventing orallowing the fluid and/or air/vapor to pass therethrough.
 12. The fluidfilter assembly of claim 1, further comprising: the interface structureincluding an interface housing having an upper interior portion incommunication with an exterior of the filter element and a lowerinterior portion that is in communication with an interior of the filterelement and is sealed with respect to the filter element; and a pressurerelief valve in communication with the upper interior portion and thelower interior portion of the interface housing of the interfacestructure for selectively allowing the fluid and/or air/vapor to passtherethrough from the upper interior portion to the lower interiorportion.
 13. The fluid filter assembly of claim 1, wherein the housingcover defines a threaded opening, the interface structure has an upperportion that is threadedly connected to the threaded opening of thehousing cover, the interface structure has a lower portion with theannular engaging part defined thereon, and the lower portion isconnected to the upper portion for rotation in unison therewith when thetorque applied to the upper portion is less than a predetermined torquevalue and for slipping with respect to the upper portion when the torqueapplied to the upper portion is greater than a predetermined torquevalue.
 14. The fluid filter assembly of claim 1, wherein the mountingmember includes a plurality of arcuate walls that extend from the axialwall of the mounting element and encircle the vent passage, wherein gapsare defined between adjacent pairs of the arcuate walls.
 15. The fluidfilter assembly of claim 1, further comprising: a divider that isconnected to the housing cover and is positioned inside the housingcover, the divider having an upper end that is sealable with respect tothe top end cap of the filter media to define an inner portion of theinterior space between the divider and filter element and an outerportion of the interior space between the divider and the housing cover.16. The fluid filter assembly of claim 15, wherein the divider includesa plurality of spacing structures that connect the divider to thehousing cover.
 17. The fluid filter assembly of claim 16, wherein thespacing structures are ribs.
 18. The fluid filter assembly of claim 15,wherein the divider is fabricated from an opaque material to blockvisibility of a fluid level in the inner portion of the interior space.19. A fluid filter assembly for filtering a fluid, comprising: a housingbase portion having an axially extending tube; a housing cover having athreaded opening, wherein the housing cover is connected to the housingbase portion to define an interior space; a filter element disposedwithin the interior space and in engagement with the axially extendingtube, the filter element having a filter media, a bottom end capconnected to the filter media, a top end cap connected to the filtermedia, and a mounting member defined by the top end cap; and aninterface structure having a upper portion that is threadedly connectedto the threaded opening of the housing cover, a lower portion that isengageable with the mounting member of the top end cap of the filterelement, and an interface ring having passages extending therethrough,wherein the lower portion is connected to the upper portion for rotationin unison therewith when the torque applied to the upper portion is lessthan a predetermined torque value and for slipping with respect to theupper portion when the torque applied to the upper portion is greaterthan a predetermined torque value, and wherein a fluid communicationchannel extends between at least the interior space, the passages of theinterface ring, and the axially extending tube.